B2 [ T or I ] to break something so that it does not separate, but very thin lines appear on its surface, or to become broken in this way（使）破裂；（使）裂开；（使）产生裂纹

[ I ] informal to become mentally and physically weak身心疲惫；神经崩溃

[ I ] informal to fail as a result of problems出现隔阂，出现问题；失败

[ I ] If someone cracks, that person begins to feel weak and agrees that they have been defeated.支持不住；崩溃，垮掉

[ T ] to break something open, especially in order to reach or use what is inside（尤指为得到或使用内部的东西而）使破裂，打开，砸开

[ T ] also crack into sth to get into someone else's computer system without permission and get information or do something illegal非法侵入（计算机系统）

[ T ] informal to copy computer programs or recorded material illegally非法复制（计算机程序或资料）

[ T ] to find a solution to a problem解决（问题）；破译

[ I or T, usually + adv/prep ] to hit something or someone碰，撞，击

[ I or T ] to make a sudden, short noise, or to cause something to make this noise（使）噼啪作响；（使）发出爆裂声

[ I ] If a voice cracks, its sound changes because the person is upset.（嗓音）变嘶哑

C1 [ T ] to make a joke or funny remark说俏皮话；开玩笑；说笑话

C2 [ C ] a very narrow space between parts of something裂缝，缝隙；裂口

[ C ] a sudden loud sound爆裂声；噼啪声

[ C usually singular ] informal an attempt努力；尝试

[ U ] also crack cocaine slang a powerful form of the drug cocaine强效纯可卡因

[ U ] → craic 愉快时光；（尤指）令人快乐的交谈

[ C ] informal a method of getting into someone else's computer system非法侵入（计算机系统）的方法

[ C ] a wisecrack （尤指用来批评的）妙语，俏皮话

excellent, or of the highest quality优秀的；顶呱呱的；第一流的